Jim Jannes

Common variants at 6p21.1 are associated with large artery atherosclerotic stroke

Genome-wide association studies (GWAS) have not consistently detected replicable genetic risk factors for ischemic stroke, potentially due to etiological heterogeneity of this trait. We performed GWAS of ischemic stroke and a major ischemic stroke subtype (large artery atherosclerosis, LAA) using 1,162 ischemic stroke cases (including 421 LAA cases) and 1,244 population controls from Australia. Evidence for a genetic influence on ischemic stroke risk was detected, but this influence was higher and more significant for the LAA subtype. We identified a new LAA susceptibility locus on chromosome 6p21.1 (rs556621: odds ratio (OR) = 1.62, P = 3.9 × 10−8) and replicated this association in 1,715 LAA cases and 52,695 population controls from 10 independent population cohorts (meta-analysis replication OR = 1.15, P = 3.9 × 10−4; discovery and replication combined OR = 1.21, P = 4.7 × 10−8). This study identifies a genetic risk locus for LAA and shows how analyzing etiological subtypes may better identify genetic risk alleles for ischemic stroke.

A multicenter, randomized, controlled study to investigate EXtending the time for Thrombolysis in Emergency Neurological Deficits with Intra-Arterial therapy (EXTEND-IA)

Background and Hypothesis Thrombolysis with tissue plasminogen activator is proven to reduce disability when given within 4.5 h of ischemic stroke onset. However, tissue plasminogen activator only succeeds in recanalizing large vessel arterial occlusion in a minority of patients. We hypothesized that anterior circulation ischemic stroke patients, selected with ‘dual target’ vessel occlusion and evidence of salvageable brain using computed tomography or magnetic resonance imaging ‘mismatch’ within 4.5 h of onset, would have improved reperfusion and early neurological improvement when treated with intra-arterial clot retrieval after intravenous tissue plasminogen activator compared with intravenous tissue plasminogen activator alone. Study Design EXTEND-IA is an investigator-initiated, phase II, multicenter prospective, randomized, open-label, blinded-endpoint study. Ischemic stroke patients receiving standard 0.9 mg/kg intravenous tissue plasminogen activator within 4.5 h of stroke onset who have good prestroke functional status (modified Rankin Scale <2, no upper age limit) will undergo multimodal computed tomography or magnetic resonance imaging. Patients who also meet dual target imaging criteria: vessel occlusion (internal carotid or middle cerebral artery) and mismatch (perfusion lesion: ischemic core mismatch ratio >1.2, absolute mismatch >10 ml, ischemic core volume <70 ml) will be randomized to either clot retrieval with the Solitaire FR device after full dose intravenous tissue plasminogen activator, or tissue plasminogen activator alone. Study Outcomes The coprimary outcome measure will be reperfusion at 24 h and favorable clinical response (reduction in National Institutes of Health Stroke Scale by ≥8 points or reaching 0–1) at day 3. Secondary outcomes include modified Rankin Scale at day 90, death, and symptomatic intracranial hemorrhage.

Adelaide Stroke Incidence Study Declining Stroke Rates but Many Preventable Cardioembolic Strokes

Background and Purpose— Stroke incidence rates are in flux worldwide because of evolving risk factor prevalence, risk factor control, and population aging. Adelaide Stroke Incidence Study was performed to determine the incidence of strokes and stroke subtypes in a relatively elderly population of 148 000 people in the Western suburbs of Adelaide. Methods— All suspected strokes were identified and assessed in a 12-month period from 2009 to 2010. Standard definitions for stroke and stroke fatality were used. Ischemic stroke pathogenesis was classified by the Trial of ORG 10172 in Acute Stroke Treatment criteria. Results— There were 318 stroke events recorded in 301 individuals; 238 (75%) were first-in-lifetime events. Crude incidence rates for first-ever strokes were 161 per 100 000 per year overall (95% confidence interval [CI], 141–183), 176 for men (95% CI, 147–201), and 146 for women (95% CI, 120–176). Adjusted to the world population rates were 76 overall (95% CI, 59–94), 91 for men (95% CI, 73–112), and 61 for women (95% CI, 47–78). The 28-day case fatality rate for first-ever stroke was 19% (95% CI, 14–24); the majority were ischemic (84% [95% CI, 78–88]). Intracerebral hemorrhage comprised 11% (8–16), subarachnoid hemorrhage 3% (1–6), and 3% (1–6) were undetermined. Of the 258 ischemic strokes, 42% (95% CI, 36–49) were of cardioembolic pathogenesis. Atrial fibrillation accounted for 36% of all ischemic strokes, of which 85% were inadequately anticoagulated. Conclusions— Stroke incidence in Adelaide has not increased compared with previous Australian studies, despite the aging population. Cardioembolic strokes are becoming a higher proportion of all ischemic strokes.

Tissue Plasminogen Activator −7351C/T Enhancer Polymorphism Is a Risk Factor for Lacunar Stroke

Background and Purpose— Occlusive thrombosis is an important component of small- and large-vessel ischemic stroke. Endogenous tissue plasminogen activator (TPA) is the primary mediator of intravascular fibrinolysis and is predominantly expressed by the endothelium of small vessels. The acute release of TPA is influenced by the TPA −7351C/T polymorphism and therefore may play an important role in the pathogenesis of lacunar stroke. In this study, we investigated the risk of lacunar and nonlacunar ischemic stroke associated with the TPA −7351C/T polymorphism. Methods— We conducted a case-control study of 182 cases of ischemic stroke and 301 community controls. Participants were evaluated for known cerebrovascular risk factors, and the TPA −7351C/T genotype was established by a polymerase chain reaction (PCR) method. Logistic regression was used to determine the risk of lacunar and nonlacunar ischemic stroke associated with the TPA −7351C/T polymorphism. Results— The prevalence of the TPA −7351 CC, CT, and TT genotypes were 46%, 45%, and 9% for controls and 41%, 46%, and 13% for stroke patients, respectively. After adjustment for known cerebrovascular risk factors, the TT genotype was significantly associated with ischemic stroke (OR: 1.9; 95% CI: 1.01 to 3.6). Stratification for stroke subtype showed a significant association between the TT genotype and lacunar stroke but not nonlacunar stroke (OR: 2.7; 95% CI: 1.1 to 6.7). Conclusions— The TPA −7351C/T polymorphism is an independent risk factor for lacunar stroke. The findings suggest that impaired fibrinolysis may play a role in the pathogenesis of lacunar stroke.

The Spot Sign and Tranexamic Acid on Preventing ICH Growth – AUStralasia Trial (STOP-AUST): Protocol of a Phase II Randomized, Placebo-Controlled, Double-Blind, Multicenter Trial

Rationale No evidence-based acute therapies exist for intracerebral hemorrhage. Intracerebral hemorrhage growth is an important determinant of patient outcome. Tranexamic acid is known to reduce hemorrhage in other conditions. Aim The study aims to test the hypothesis that intracerebral hemorrhage patients selected with computed tomography angiography contrast extravasation ‘spot sign’ will have lower rates of hematoma growth when treated with intravenous tranexamic acid within 4·5-hours of stroke onset compared with placebo. Design The Spot sign and Tranexamic acid On Preventing ICH growth – AUStralasia Trial is a multicenter, prospective, 1:1 randomized, double-blind, placebo-controlled, investigator-initiated, academic Phase II trial. Intracerebral hemorrhage patients fulfilling clinical criteria (e.g. Glasgow Coma Scale >7, intracerebral hemorrhage volume <70 ml, no identified secondary cause of intracerebral hemorrhage, no thrombotic events within the previous 12 months, no planned surgery) and demonstrating contrast extravasation on computed tomography angiography will receive either intravenous tranexamic acid 1 g 10-min bolus followed by 1 g eight-hour infusion or placebo. A second computed tomography will be performed at 24 ± 3 hours to evaluate intracerebral hemorrhage growth and patients followed up for three-months. Study outcomes The primary outcome measure is presence of intracerebral hemorrhage growth by 24 ± 3 hours, defined as either >33% or >6 ml increase from baseline, and will be adjusted for baseline intracerebral hemorrhage volume. Secondary outcome measures include growth as a continuous measure, thromboembolic events, and the three-month modified Rankin Scale score. Discussion This is the first trial to evaluate the efficacy of tranexamic acid in intracerebral hemorrhage patients selected based on an imaging biomarker of high likelihood of hematoma growth. The trial is registered as NCT01702636.

Ischaemic stroke among young people aged 15 to 50 years in Adelaide, South Australia.

Objectives: To report risk factors, aetiology and neuroimaging features among a large series of young Australian patients who were admitted to hospital for a first‐ever occurrence of ischaemic stroke; to analyse the effect of age, sex and ethnicity on the presence of risk factors; and to compare Australian and overseas data.

Determining the Number of Ischemic Strokes Potentially Eligible for Endovascular Thrombectomy: A Population-Based Study

Background and Purpose— Endovascular thrombectomy (ET) is standard-of-care for ischemic stroke patients with large vessel occlusion, but estimates of potentially eligible patients from population-based studies have not been published. Such data are urgently needed to rationally plan hyperacute services. Retrospective analysis determined the incidence of ET-eligible ischemic strokes in a comprehensive population-based stroke study (Adelaide, Australia 2009–2010). Methods— Stroke patients were stratified via a prespecified eligibility algorithm derived from recent ET trials comprising stroke subtype, pathogenesis, severity, premorbid modified Rankin Score, presentation delay, large vessel occlusion, and target mismatch penumbra. Recognizing centers may interpret recent ET trials either loosely or rigidly; 2 eligibility algorithms were applied: restrictive (key criteria modified Rankin Scale score 0–1, presentation delay <3.5 hours, and target mismatch penumbra) and permissive (modified Rankin Scale score 0–3 and presentation delay <5 hours). Results— In a population of 148 027 people, 318 strokes occurred in the 1-year study period (crude attack rate 215 [192–240] per 100 000 person-years). The number of ischemic strokes eligible by restrictive criteria was 17/258 (7%; 95% confidence intervals 4%–10%) and by permissive criteria, an additional 16 were identified, total 33/258 (13%; 95% confidence intervals 9%–18%). Two of 17 patients (and 6/33 permissive patients) had thrombolysis contraindications. Using the restrictive algorithm, there were 11 (95% confidence intervals 4–18) potential ET cases per 100 000 person-years or 22 (95% confidence intervals 13–31) using the permissive algorithm. Conclusions— In this cohort, ≈7% of ischemic strokes were potentially eligible for ET (13% with permissive criteria). In similar populations, the permissive criteria predict that ⩽22 strokes per 100 000 person-years may be eligible for ET.

Genetic Overlap Between Diagnostic Subtypes of Ischemic Stroke

Background and Purpose— Despite moderate heritability, the phenotypic heterogeneity of ischemic stroke has hampered gene discovery, motivating analyses of diagnostic subtypes with reduced sample sizes. We assessed evidence for a shared genetic basis among the 3 major subtypes: large artery atherosclerosis (LAA), cardioembolism, and small vessel disease (SVD), to inform potential cross-subtype analyses. Methods— Analyses used genome-wide summary data for 12 389 ischemic stroke cases (including 2167 LAA, 2405 cardioembolism, and 1854 SVD) and 62 004 controls from the Metastroke consortium. For 4561 cases and 7094 controls, individual-level genotype data were also available. Genetic correlations between subtypes were estimated using linear mixed models and polygenic profile scores. Meta-analysis of a combined LAA–SVD phenotype (4021 cases and 51 976 controls) was performed to identify shared risk alleles. Results— High genetic correlation was identified between LAA and SVD using linear mixed models (rg=0.96, SE=0.47, P=9×10−4) and profile scores (rg=0.72; 95% confidence interval, 0.52–0.93). Between LAA and cardioembolism and SVD and cardioembolism, correlation was moderate using linear mixed models but not significantly different from zero for profile scoring. Joint meta-analysis of LAA and SVD identified strong association (P=1×10−7) for single nucleotide polymorphisms near the opioid receptor &mgr;1 (OPRM1) gene. Conclusions— Our results suggest that LAA and SVD, which have been hitherto treated as genetically distinct, may share a substantial genetic component. Combined analyses of LAA and SVD may increase power to identify small-effect alleles influencing shared pathophysiological processes.

Are Myocardial Infarction–Associated Single-Nucleotide Polymorphisms Associated With Ischemic Stroke?

Background and Purpose— Ischemic stroke (IS) shares many common risk factors with coronary artery disease (CAD). We hypothesized that genetic variants associated with myocardial infarction (MI) or CAD may be similarly involved in the etiology of IS. To test this hypothesis, we evaluated whether single-nucleotide polymorphisms (SNPs) at 11 different loci recently associated with MI or CAD through genome-wide association studies were associated with IS. Methods— Meta-analyses of the associations between the 11 MI-associated SNPs and IS were performed using 6865 cases and 11 395 control subjects recruited from 9 studies. SNPs were either genotyped directly or imputed; in a few cases a surrogate SNP in high linkage disequilibrium was chosen. Logistic regression was performed within each study to obtain study-specific &bgr;s and standard errors. Meta-analysis was conducted using an inverse variance weighted approach assuming a random effect model. Results— Despite having power to detect odds ratio of 1.09–1.14 for overall IS and 1.20–1.32 for major stroke subtypes, none of the SNPs were significantly associated with overall IS and/or stroke subtypes after adjusting for multiple comparisons. Conclusions— Our results suggest that the major common loci associated with MI risk do not have effects of similar magnitude on overall IS but do not preclude moderate associations restricted to specific IS subtypes. Disparate mechanisms may be critical in the development of acute ischemic coronary and cerebrovascular events.

Smoking termination opportunity for in patients (STOP): superiority of a course of varenicline tartrate plus counselling over counselling alone for smoking cessation: a 12-month randomised controlled trial for inpatients

Rationale Smoking cessation interventions in outpatient settings have been demonstrated to be cost effective. Given this evidence, we aimed to evaluate the effectiveness of varenicline tartrate plus Quitline-counselling compared with Quitline-counselling alone when initiated in the inpatient setting. Methods Adult patients (18–75 years) admitted with a smoking-related illness to three hospitals, were randomised to receive either 12-weeks of varenicline tartrate plus Quitline-counselling, (n=196) or Quitline-counselling alone, (n=196), with 12-months follow-up. Results For the primary analysis population (intention-to-treat), the proportion of subjects who remained continuously abstinent were significantly greater in the varenicline plus counselling arm (31.1%, n=61) compared with counselling alone (21.4%, n=42; RR 1.45, 95% CI 1.03 to 2.03, p=0.03). Conclusions The combined use of varenicline plus counselling when initiated in the inpatient setting has produced a sustained smoking cessation benefit at 12-months follow-up, indicating a successful opportunistic treatment for smokers admitted with smoking related illnesses. Trial registration http://www.clinicaltrials.gov/ ClinicalTrials.gov identification number: NCT01141855.